Old Faithful is a cone geyser in Yellowstone National Park in Wyoming. It is notable for erupting every 44 minutes to two hours since 2000.
In "The Professor and the Coach", Roger's persona of Professor Longbottom disappears after a bad review of his book about Old Faithful. Hayley confronts his football Coach Grundy persona who has taken over his life and discovers that he has written a book of his own. Flipping though the coach's book, she realizes that he's incorporated parts of the professor's work and hopes to bring out that part of him again. A page in the book directs her to travel to Old Faithful, and Roger's coach comes along for the ride. They find the professor, but it turns out to be a trap by the coach who knocks them out with ether. When they come to, they find themselves dangling over Old Faithful to be killed when the geyser erupts. The professor frees himself to confront the coach, leaving Hayley behind with Rogu serving in his place. Reading the professor's book, the coach decides to have a change of heart and saves Hayley and Rogu.